Influence of glacial water and carbonate minerals on wintertime sea-ice biogeochemistry and the CO 2 system in an Arctic fjord in Svalbard

• Published in: Annals of Glaciology
• Main Authors: Fransson, Agneta, Chierici, Melissa, Nomura, Daiki, Granskog, Mats A., Kristiansen, Svein, Martma, Tõnu, Nehrke, Gernot
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2020
• Subjects: Arctic; Svalbard; Tempelfjorden; Annals of Glaciology; glacier; Sea ice; Tempelfjord*
• Online Access: http://dx.doi.org/10.1017/aog.2020.52; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S026030552000052X

Abstract The effect of freshwater sources on wintertime sea-ice CO 2 processes was studied from the glacier front to the outer Tempelfjorden, Svalbard, in sea ice, glacier ice, brine and snow. March–April 2012 was mild, and the fjord was mainly covered with drift ice, in contrast to the observed thicker fast ice in the colder April 2013. This resulted in different physical and chemical properties of the sea ice and under-ice water. Data from stable oxygen isotopic ratios and salinity showed that the sea ice at the glacier front in April 2012 contained on average 54% of frozen-in glacial meltwater. This was five times higher than in April 2013, where the ice was frozen seawater. In April 2012, the largest excess of sea-ice total alkalinity ( A T ), carbonate ion ([CO 3 2− ]) and bicarbonate ion concentrations ([HCO 3 − ]) relative to salinity was mainly related to dissolved dolomite and calcite incorporated during freezing of mineral-enriched glacial water. In April 2013, the excess of these variables was mainly due to ikaite dissolution as a result of sea-ice processes. Dolomite dissolution increased sea-ice A T twice as much as ikaite and calcite dissolution, implying different buffering capacity and potential for ocean CO 2 uptake in a changing climate.